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A324884 a(1) = 0; for n > 1, a(n) = A001511(A324819(n)), where A324819(n) = 2*A156552(n) OR A323243(n).

%I A324884 #10 Mar 28 2019 20:23:47
%S A324884 0,1,1,2,1,2,1,2,3,1,1,2,1,2,2,2,1,2,1,2,1,2,1,2,3,2,3,2,1,2,1,2,2,2,
%T A324884 2,2,1,2,3,2,1,2,1,2,3,2,1,2,3,1,3,2,1,2,1,2,3,2,1,2,1,2,3,2,2,2,1,2,
%U A324884 2,2,1,2,1,2,2,2,2,2,1,2,3,2,1,2,4,2,3,2,1,2,1,2,2,2,3,2,1,1,3,2,1,2,1,2,3
%N A324884 a(1) = 0; for n > 1, a(n) = A001511(A324819(n)), where A324819(n) = 2*A156552(n) OR A323243(n).
%C A324884 Terms 0 .. k occur for the first time at n = 1, 2, 4, 9, 85, 133, 451, 1469, 2159, 2489, 4393, 7279, ..., which after 2 seem all to be semiprimes, that is, A156552(n) has binary weight 2.
%H A324884 Antti Karttunen, <a href="/A324884/b324884.txt">Table of n, a(n) for n = 1..10000</a> (based on Hans Havermann's factorization of A156552)
%H A324884 <a href="/index/Pri#prime_indices">Index entries for sequences computed from indices in prime factorization</a>
%H A324884 <a href="/index/Si#SIGMAN">Index entries for sequences related to sigma(n)</a>
%F A324884 a(1) = 0; for n > 1, a(n) = A001511(A324819(n)).
%F A324884 a(n) = A324882(n) + A324883(n).
%F A324884 a(p) = 1 for all primes p.
%o A324884 (PARI)
%o A324884 A156552(n) = {my(f = factor(n), p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res}; \\ From A156552
%o A324884 A324819(n) = bitor(2*A156552(n),A323243(n)); \\ Needs code also from A323243.
%o A324884 A001511ext(n) = if(!n,n,sign(n)*(1+valuation(n,2))); \\ Like A001511 but gives 0 for 0 and -A001511(-n) for negative numbers.
%o A324884 A324884(n) = A001511ext(A324819(n));
%Y A324884 Cf. A001511, A156552, A323243, A324819, A324882, A324883.
%K A324884 nonn
%O A324884 1,4
%A A324884 _Antti Karttunen_, Mar 28 2019